This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 120 |
| 3 | 210 |
| 4 | 1540 |
| 5 | 3003 |
| 6 | 7140 |
| 7 | 11628 |
| 8 | 24310 |
| 9 | 61218182743304701891431482520 |